These cap head hex socket screws are made of carbon steel with a black oxide finish, offering rust and corrosion resistance. They are available in 9 thread lengths for versatile use in home and office appliances, machinery, furniture, communication equipment, and industrial applications. 1. Carbon steel construction with black oxide finish provides high tensile strength and corrosion resistance in various environments. 2. Cap head design allows for driving in tight spaces where wrenches cannot fit. 3. Ideal for applications requiring a flush or countersunk installation. 4. Suitable for general-purpose fastening in appliances, electronics, machinery, and assembly tasks. 5. Screws and nuts are organized in 10 labeled compartments inside a transparent plastic storage box for easy access and organization. Material: Carbon steel Finish: Black oxide Thread Diameter: M3 (3 mm) Thread Lengths: 4 mm (20 pcs), 5 mm (20 pcs), 6 mm (20 pcs), 8 mm (20 pcs), 10 mm (20 pcs), 12 mm (20 pcs), 16 mm (20 pcs), 20 mm (20 pcs), 25 mm (20 pcs) Package Dimensions: 12.5 × 6.2 × 2.2 cm Type: Cap Head Hex Socket Screw Function: Fastener Package Includes: 180 screws, 100 nuts